#LasVegas planners design third intake pump station for the day the #ColoradoRiver stops at #HooverDam #COriver #aridification

To address unprecedented drought conditions and provide long-term protection of Southern Nevada’s primary water storage reservoir—Lake Mead— the Southern Nevada Water Authority constructed a third drinking water intake capable of drawing upon Colorado River water at lake elevations below 1,000 feet (above sea level). Intake No. 3 ensures Southern Nevada’s access to its primary water supply if lake levels continue to decline due to drought conditions. It also protects municipal water customers from water quality issues associated with declining lake levels. Photo credit: Southern Nevada Water Authority

From The Nevada Independent (Daniel Rothberg):

It is hard to fathom, but there is a possible future in which this section of the river — the source of water for millions of Americans from farmers in the Imperial Valley to residents of Phoenix — could dry to a trickle.

That doomsday scenario, if it happens, is still far away. But without cutbacks to water use across the Southwest, it could one day play itself out, especially under drier hydrologic conditions driven by climate change. And it’s scary enough for Las Vegas, which gets 90 percent of its municipal water from the Colorado River, that the city has been spending big money to hedge its bets.

“You have a lot of people in Vegas who are very good at making bets,” said Jonathan Overpeck, a dean at the University of Michigan’s environmental school and a Colorado River researcher. “[The Southern Nevada Water Authority] is making a bet that it should spend $1.3 billion so that it can get [it’s full allocation], even at dead pool. So I would say that it is a possibility, then.”

[…]

That water users would let the system crash to dead pool is unlikely. To let the once wild river stop at the dam’s edge would be a political and ecological disaster.

“My gut feeling is we never get there. A whole lot of institutional systems would have to fail to get the lake that low,” said John Fleck, a professor at the University of New Mexico who wrote a book about the Colorado River. “At that point when we get the lake that low, we have huge problems across the West. I am confident that we never get to the point where the lake gets that low, because I am confident that the water management community will never let that happen.”

But the improbable scenario is still one Las Vegas is working to secure itself against.

On Tuesday, thousands of yards upstream and about 300 feet below the reservoir’s surface, water authority contractors continued working underground on a pumping station that would protect the city from dead pool if Lake Mead ever dropped to that point. Experts who study Colorado River politics have said that the infrastructure project has changed Las Vegas from one of the least secure cities on the river to one of the most secure cities. When it is completed in 2020, Las Vegas would be the only water user in the lower Colorado River basin that could get water under dead pool conditions.

“This project is drought driven,” Erika Moonin, a project manager for the water authority, told reporters Tuesday before a tour of the pumping station. “It will allow us to have continued access to our community water supply even if the lake levels get to very extreme low levels.”

The pumping station will connect to the water authority’s so-called third intake, a straw that allows for access to water deep in the reservoir. Together both projects are expected to cost about $1.35 billion and will give the water authority the ability to pump water below dead pool. But the worst-case scenario is not the only reason the water authority wanted the intake.

There are other advantages.

Chief among them is that the water authority’s current pumping infrastructure — at 1,000 feet above sea level — will become inoperable even before the reservoir hits dead pool, which will occur at 895 feet above sea level. The reservoir’s surface currently sits at about 1,078 feet. The station will also allow the agency to access colder, higher-quality water in the reservoir, which is easier to treat.

Before the third intake was completed, Las Vegas was at risk of having nearly its entire water supply cut off if the reservoir fell below 1,000 feet. That meant no water to a metropolitan area of more than 2 million. Now with the completion of the pumping station, Las Vegas will have a security that no other Lake Mead water user has: the ability to take out water at dead pool.

“Our delivery mechanism is guaranteed under all hydrologic conditions,” John Entsminger, the water authority’s general manager, said in an interview with The Nevada Independent in August. “That’s not true for anyone downstream of us. From a physical water security standpoint, Las Vegas is better off than any other metropolitan area that takes water from the Colorado River.”

[…]

On Tuesday, about 300 feet below Lake Mead’s current elevation, pumps cleared groundwater that was seeping into the cavern. The hot water, in an area with high thermal activity, has scored the sides of the cave with calcium and iron deposits as it has dripped down the cave’s 40-foot walls.

In the coming weeks, construction crews plan to remove those pumps, allowing groundwater to fill the area at a rate of roughly 500 gallons per minute. Then, using a submarine, the contractor will remove a bulkhead holding back water from the reservoir, a key milestone. But the site will still not be operable for many months until pumps are installed and a substation is built.

South of Lake Mead, water still flows out of Hoover Dam and downstream. If the worst-case scenario played itself out and water one day stopped snaking past the dam, river-dependent cities and Southwest agriculture would not be the only collateral damage. Dead pool would cripple the environment to the south, adding the absolute insult to injury for many environmentalists who already decry dams as unnatural obtrusions.

“You can almost see the Colorado River and Lake Mead as a microcosm for the way that we have treated the environment, particularly in the Western United States, by corralling and controlling resources to achieve an ideal,” said Patrick Donnelly, the Nevada state director for the Center for Biological Diversity. “[Lake Mead is] an emblem to control the West.”

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.